PSY240H5 Lecture Notes - Lecture 1: Social Stigma, Operant Conditioning, Aaron T. Beck
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Etiology for schizophrenia
early theories poor parenting and maternal rejections are triggers of schizophrenia.
Social class-illness view link exposure to poverty, crime and family disturbance led to
increased cases of schizophrenia.
Nongenetic risk factors
pre-natal and birth environment
o complications during birth may cause brain dysfunction/damage (e.g., nutritional)
o obstetrical and birth complications (e.g., caesarean section, anoxia at birth)
season of birth
o prenatal virus exposure (influenza virus exposure during second trimester)
Usually winter(october –may)
o vitamin d deficiency
Seasonal effect and 2nd trimester
Seasonal effect – people born in late winter, early spring much more likely to develop
Maternal exposure to viruses during pregnancy
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expressed emotion (ee)
cultural differences in ee
suggests ee is not a major causal factor
(since prevalence is stable)
The stress-diathesis model: etiology (cont’d)
no single cause has been identified
combination of various environmental factors create a vulnerable state which
triggers the onset of the disease in early adulthood if that person is genetically
o cross-cultural consistency
o improved prognosis in developing countries
o family dynamics, e.g., expressed emotion (criticism, hostility, over-involvement)
social status – ses inversely related to rates of schizophrenia; social selection vs. Social
psychiatric conditions are outcome of inherited, biologically based vulnerabilities that
interact with environmental stresses to push individuals into developing psychosis.
the assumption is that both diathesis and stress are required.
meehl’s theory proposes a diathesis stress called hypokrisia
oHypokrisia is the hypersensitivity of nerve cells in the brain to incoming
stimulations(such as env).
o this causes cognitive slippage(information becomes incoherent and causes
o the brain amplifies feelings of pain and weakens pleasure withdrawal for
oSchizotype is the person experiencing cognitive slippage and aversive
Neurodevelopmental-diathesis stress theories suggest that early brain injury during
fetal development may become a diathesis.
having a biological relative with schizophrenia increases the risk.
Schizophrenia have a strong genetic factor
Many genes variation associated with schizophrenia
Only 48% concordance with mz twins not fully genetic
there are discrepancies between predicted and observed cases of genetic illnesses
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